Golf ball having multiple different coating layers

ABSTRACT

A golf ball comprising core; a cover disposed about the core; and a coating system disposed about the cover having at least three layers: a first coating layer C 1  surrounding the cover; a second coating layer C 2  surrounding C 1 ; and a third coating layer C 3  surrounding C 2 ; wherein C 1  has a first color appearance A 1 , C 2  has a second color appearance A 2 , and C 3  has a third color appearance A 3  such that A 1 ≠A 2 ≠A 3  and wherein A 1 , A 2 , and A 3  each contribute to an overall golf ball color appearance. A method of making the inventive golf ball comprises: providing a core and a cover disposed about the core; and providing a coating system about the cover comprising C n  coating layers wherein n≧3, and wherein each of the C n  coating layers have a different color appearance contributing to the overall golf ball color appearance.

FIELD OF THE INVENTION

Golf balls incorporating color and color effects in multiple coating layers to improve golf ball durability and adhesion between coating layers.

BACKGROUND OF THE INVENTION

Golf is a game of confidence. So much so, that a golfer's confidence level during a given round is often outcome determinative. In this regard, an aesthetically pleasing and superiorly constructed golf ball is a great confidence builder. For this reason, golfers typically carefully settle on an ultimate golf ball of choice by visually comparing each golf ball possessing their particular desired playing characteristics.

Golf ball coating layers not only add aesthetic appeal but also provide overall golf ball protection, an attribute related to quality. Initially, two types of coating systems developed: colored (opaque) and clear. Opaque white coatings were first applied to golf balls since most golfers traditionally enjoyed a white colored golf ball. An outermost (clear) coating layer was also applied over surface indicia such as logos or other designs to protect these markings and the overall golf ball surface. Both types of coatings have been applied in single or multiple applications, i.e. one-coat, two-coat, etc.

In the 1980s, following the introduction of ionomer cover materials, golf ball manufacturers began to incorporate the preferred white color (as well as other colors) directly into the cover, theoretically eliminating the need for a white or colored coating. However, incorporating the preferred white color directly into the cover met substantial disadvantages and drawbacks. For example, some of the most preferred cover materials either do not match the ideal shade of white color or else transition over time from an initial desirable shade of white to a less visually appealing one—often referred to as “yellowing”. Balata and aromatic urethane compositions are two such golf ball cover materials generally requiring an opaque white coating system in order to achieve and/or maintain the preferred/optimum white color shade.

Thus, coating a golf ball outermost surface has remained a desirable option, and manufacturers continue to look to improve coating systems in order to produce the most aesthetically pleasing and durable golf ball. While prior golf ball coating systems have included as many as three coating layers, two of the three coating layers heretofore have been substantially similar. For example, one common conventional coating system consists of a three-coat process wherein the first two applications are white and the final third coating is a protective clear coating.

In this regard, golf ball manufacturers applied the white coating in two applications for two specific reasons. Firstly, two applications better reduces or eliminates imperfections (defects) occurring the application process. In particular, as balls sit upon spindles when sprayed and are subsequently transferred from the spindles to trays for drying, the spindle, transfer picks and trays can all leave small marks/nicks on the golf ball surface which a second application of the white coating can mask or cover.

Secondly, the most preferred coatings are thin and uniform because heavy applications are more prone to surface defects and more substantially affect the flight of the ball. Thus, applying two lighter white coats rather than one heavy coat assures more uniform coverage at a lower overall application rate. In general, a coating must be thick enough to possess excellent “hiding power” yet be thin enough to preserve golf ball performance characteristics and not compromise a golf ball's strength (durability or abrasion resistance).

Further, fairly recently, golf ball manufacturers have begun incorporating interference effect pigmentation in coatings to improve and enhance overall golf ball appearance. One such golf ball uses a two-coat system comprising a white paint formed about the golf ball outermost surface and a top coat incorporating an effects pigment providing optical interference. However, this two-layer coating golf ball presented durability issues when particles made the golf ball surface vulnerable to breaks in the surface when a club struck the golf ball. Yet, it is not practical to place the interference effects coating layer beneath the opaque coating layer for the obvious reason that an overlying opaque coating layer would totally block any visibility of the interference effects layer beneath it.

Another prior golf ball is a three layer coating system incorporating one coating layer having interference effect pigmentation underneath two clear/transparent coating layers. In this construction, the underlying cover color is visible through the coating layers, producing a deficient and undesirable overall golf ball color appearance where the underlying cover is white, which yellows over time due to UV degradation.

Accordingly, there remains a need for golf balls incorporating coating systems having at least three coating layers each which contribute to an overall golf ball color appearance imparting/producing interference effects or a pearl luster without compromising golf ball durability and adhesion as between coating layers. The current invention addresses and solves this need.

SUMMARY OF THE INVENTION

A golf ball of the present invention comprises an uncoated “substrate golf ball” and a coating system including at least three coating layers disposed about the substrate golf ball. The substrate golf ball may have any construction known in the art, including an outermost surface or cover layer about which the coating system is formed. The outermost surface or cover layer may comprise dimples or other indentations and/or protrusions.

A golf ball of the invention possesses a unique strong, vivid and/or vibrant overall golf ball color appearance. In one embodiment, the golf ball comprises a core, a cover disposed about the core, an innermost coating layer C₁ surrounding the cover, an intermediate coating layer C₂ surrounding C₁, and an outermost coating layer C₃ surrounding C₂, wherein C₁ has a first color appearance A₁, C₂ has a second color appearance A₂, and C₃ has a third color appearance A₃ wherein A₁≠A₂≠A₃, and wherein A₁, A₂, and A₃ contribute to an overall golf ball color appearance.

Non-limiting examples of the at least three different coating layers of a golf ball of the invention are as follows. In one embodiment of a golf ball of the invention, C₁ is an opaque coating, C₂ is a translucent coating having effect pigmentation such as a pearlescent pigment having sufficient hiding power to mask manufacturing artifacts such as spindle, pick and tray marks and yet provide or impart a special optical effect; and C₃ is a transparent coating. In this embodiment, C₁ may be a solid color, including a white pigment or a pigment other than white. The color of C₁ may be identical to the color of the substrate (the golf ball outermost surface), may be identical in hue to that of the substrate but vary in chroma or saturation, or may instead have a different hue than that of the substrate. Meanwhile, since C₂ is translucent, C₁ at least partially contributes to the overall golf ball appearance. And C₃ may be either transparent colorless or transparent and impart color (transparent colored).

In a different embodiment, C₁ is translucent, C₂ is also translucent, but differs from C₁ in a respect such as in hue or dominant hue, saturation, chroma, reflectance, transmittance and/or thickness, and C₃ is transparent and may alternatively be transparent and impart color. For example, in one embodiment, C₁ is translucent and comprises a red pearlescent pigment, C₂ is translucent and comprises a gold pearlescent pigment, and C₃ is transparent. In another embodiment, C₁ is translucent and comprises a gold pearlescent pigment, C₂ is translucent and comprises a green pearlescent pigment, and C₃ is transparent. In yet another non-limiting embodiment, C₁ is translucent and comprises a red pearlescent pigment, C₂ is translucent and comprises a gold pearlescent pigment, and C₃ comprises a transparent orange color.

An inventive golf ball may further comprise a marking M formed on a portion of the golf ball surface area over C₂, and surrounded by C3. Additional non-limiting examples of coating layer arrangements are included in TABLE I and TABLE III herein below.

A golf ball of the invention is not limited to three coating layers and may comprise C_(n) coating layers disposed about the outermost golf ball surface wherein n≧3, and wherein each of C_(n) coating layers has a different color appearance that contributes to an overall color appearance. For example, in one embodiment, n=4 such that: C₁ is opaque and comprises a white pigment; C₂ is translucent and comprises a gold pearl interference effects pigment; C₃ is translucent and comprises a red pearl interference effects pigment; and C₄ is transparent. In another embodiment, n=4 such that: C₁ is opaque and comprises a red pigment; C₂ is translucent and comprises a gold pearl interference effects pigment; C₃ is translucent and comprises a red pearl interference effects pigment; and C₄ comprises a transparent yellow color. C₄ may in another embodiment be identical to one of C₁, C₂, and C₃.

In another embodiment, the inventive golf ball comprises C_(n) coating layers disposed about the outermost golf ball surface wherein n≧4, wherein at least 3 of the C_(n) coating layers has a different color appearance that contributes to an overall color appearance.

The C_(n) coating layers may be different as having differing degrees of opacity or translucency; or as being different as being transparent versus transparent and imparting color; or being different as being opaque versus translucent versus transparent; or having different hues, chromas, saturations, thicknesses, reflectances, transmittances as these terms are recognized and measured in the art. For example, in one embodiment, C₁ has a reflectance R₁, C₂ has a reflectance R₂, and C₃ has a reflectance R₃ such that R₁≠R₂≠R₃. In another embodiment, C₁ has a transmittance T₁, C₂ has a transmittance T₂ and C₃ has a transmittance T₃ such that T₁≠T₂≠T₃.

In yet another embodiment n=4 such that: C₁ and C₂ are both opaque and comprise a white pigment; C₃ is translucent and comprises an interference effects pigment; and C₄ is transparent. In one embodiment, C₁, C₂, C₃, and C₄ have corresponding transmittances C_(1T), C_(2T), C_(3T), and C_(4T) such that C_(1T) is substantially similar to C_(2T) and C_(2T)≠C_(3T)≠C_(4T). In another embodiment, C₁, C₂, C₃, and C₄ have corresponding reflectances C_(1R), C_(2R), C_(3R), and C_(4R) such that C_(1R) is substantially similar to C_(2R) and C_(2R)≠C_(3R)≠_(4R).

Further, reflectance may be either specular or diffuse. Reflectance is specular where, for a given normal to the golf ball surface, the inclination (angle) of the reflected beam (light outgoing from the golf ball surface) is either: (1) identical to the inclination of the incident light (incoming light toward the golf ball surface); or (2) is scattered about only in the specular direction. On the other hand, reflectance is diffuse where the inclination of the reflected light is scatterd in all directions. See, e.g., Paint and Coating Testing Manual, Part 10, Chapter 40, “Color and Light” by Fred W. Billmeyer and Harry K. Hammond (MNL 17-EB/June 1995)© 1995 ASTM International; and http://www.physicsclassroom.com/class/refln/u1311d.cfm. Reflectance may be measured by any method known in the art capable of detecting and/or measuring a reflectance differential as between the coating layers including, for example, ASTM E1331-04, “Standard Test Method for Reflectance Factor and Color by Spectrophotometry Using hemispherical Geometry”.

Transmittance may be measured by any method known in the art capable of detecting and/or measuring a transmittance differential as between the coating layers including, for example, ASTM E1348-02, “Standard Test Method for Transmittance and Color by Spectrophotometry Using hemispherical Geometry”. Transmittance may be diffuse or regular, depending on whether or not light scatters when it passes through the coating material.

The visual appearance of a coating layer may be changed by varying the thickness of the coating, especially in a translucent coating layer, for example. Non-limiting examples of thicknesses of a coating layer in a golf ball of the invention are as follows. In one embodiment, a golf ball of the invention may have an overall (combined) coating layer thickness of from about 0.1μ to about 100μ. In another embodiment, a golf ball of the invention may have an overall coating thickness of from about 7μ to about 45μ.

Additionally, non-limiting examples of individual coating layer thicknesses are as follows. In one embodiment, at least one coating layer has a thickness of from about 2μ to about 14μ. In another embodiment, at least one coating layer has a thickness of from about 3μ to about 17μ. In yet another embodiment, at least one coating layer has a thickness of from about 5μ to about 11μ. In still another embodiment, at least one coating layer has a thickness of from about 7μ to about 9μ. In an alternative embodiment, at least one coating layer has a thickness of from about 6μ to about 12μ. In a different embodiment, at least one coating layer has a thickness of from about 8μ to about 12μ.

Moreover, in a golf ball of the invention, the relative thicknesses as between respective coating layers may be set and contributes to and influences the overall color appearance, especially in translucent coating layers. In one embodiment, C₁ has a thickness TH₁, C₂ has a thickness TH₂, and C₃ has a thickness TH₃, wherein TH₁≠TH₂≠TH₃. In another embodiment, TH₁<TH₂<TH₃. In yet another embodiment, TH₁>TH₂>TH₃. In still another embodiment, TH₁<TH₂>TH₃. In a different embodiment, TH₁>TH₂<TH₃.

Where a translucent coating contains an amount of interference effect pigment or colorant, the pigment loading level of either may also be varied to alter the appearance of the coating and therefore overall golf ball appearance.

In another embodiment, a golf ball of the invention comprises a three layer coating comprising an innermost coating layer adjacent the cover, an intermediate coating layer surrounding the innermost coating layer, and an outermost coating layer surrounding the intermediate coating layer, wherein each of the three coating layers has a different color appearance that contributes to an overall golf ball color appearance producing a color traveling effect. In this embodiment, the three coating layers are strategically formulated and coordinated with each other based on how the human eye perceives the spectral composition of light being transmitted and/or reflected by the golf ball surface. Each coating layer contributes differently to the color travelling effect. In one embodiment, the innermost coating layer contributes X % to the color traveling effect, the intermediate coating layer contributes Y % to the color traveling effect, and the outermost coating layer contributes Z % to the color traveling effect, wherein X %≠Y %≠Z %.

Herein, the term “color traveling effect” as used herein refers to iridescence or goniochromism created by a coating on the golf ball surface wherein the golf ball surface appears to change color as the viewing angle or the angle of illumination changes. See, e.g. U.S. Pat. No. 7,220,192 of Andre et al., incorporated by reference herein in its entirety. Non-limiting examples of suitable interference effect pigments include metal-oxide coated mica based pigments, metal-oxide coated aluminum oxide platelets and metal-oxide coated silica platelets involving interference, reflection and absorption phenomena; calcium aluminum borosilicate coated with a metal oxide; silicon dioxide platelets coated with metal oxide; and an iron oxide pigment substrate coated with a metal oxide.

In a golf ball of the invention, the substrate (portion of the golf ball other than the coating system) may comprise any type or combination of golf ball components known in the art as well as may comprise any suitable compositions/materials. Non-limiting examples of golf ball substrates and compositions/materials are discussed in detail below.

The invention is also directed to method of making a golf ball of the invention comprising: providing a core and a cover disposed about the core; forming a first coating layer C₁ about the cover; forming a second coating layer C₂ about C₁; and forming a third coating layer C₃ about C₂; wherein C₁ has a first color appearance A₁, C₂ has a second color appearance A₂, and C₃ has a third color appearance A₃ such that A₁≠A₂≠A₃ and wherein A₁, A₂, and A₃ each contribute to an overall golf ball color appearance. In another embodiment, the method of making a golf ball comprises: providing a core and a cover disposed about the core; and providing a coating system about the cover comprising C_(n) coating layers wherein n≧3 and wherein each of the C_(n) coating layers has a different color appearance that contributes to an overall golf ball color appearance.

DETAILED DESCRIPTION

The cores in golf balls of this invention may be solid, semi-solid, hollow, fluid-filled, or powder-filled. Typically, the cores are solid and made from rubber compositions containing at least a base rubber, free-radical initiator agent, cross-linking co-agent, and fillers. Golf balls having various constructions may be made in accordance with this invention. For example, golf balls having three-piece, four-piece, and five-piece constructions with dual or three-layered cores and cover materials may be made. More particularly, in one version, a three-piece golf ball comprising a center and a “dual-cover” is made. In another version, a four-piece golf ball comprising a dual-core and “dual-cover” is made. The dual-core includes an inner core (center) and surrounding outer core layer. The dual-cover includes inner cover and outer cover layers. In yet another construction, a five-piece golf ball having a dual-core, intermediate layer, and dual-cover is made. In still another embodiment, a four piece golf ball comprises a core and a three layer cover.

As used herein, the term, “intermediate layer” means a layer of the golf ball disposed between the core (center or outer core layer) and cover. The intermediate layer may be considered an outer core layer, or inner cover layer, or any other layer disposed between the inner core and outer cover of the ball. The diameter and thickness of the different layers along with properties such as hardness and compression may vary depending upon the construction and desired playing performance properties of the golf ball and as specified herein.

The inner core of the golf ball may comprise a polybutadiene rubber material. In one embodiment, the ball contains a single core formed of the polybutadiene rubber composition. In a second embodiment, the ball contains a dual-core comprising an inner core (center) and surrounding outer core layer. In yet another version, the golf ball contains a multi-layered core comprising an inner core, intermediate core layer, and outer core layer.

In general, polybutadiene is a homopolymer of 1,3-butadiene. Any suitable catalyst may be used to synthesize the polybutadiene rubber depending upon the desired properties. Normally, a transition metal complex (for example nickel, or cobalt), a rare earth metal such as neodymium or an alkyl metal such as alkyllithium is used as a catalyst. Other catalysts include, but are not limited to, aluminum, boron, lithium, titanium, and combinations thereof. The catalysts produce polybutadiene rubbers having different chemical structures. In a cis-bond configuration, the main internal polymer chain of the polybutadiene appears on the same side of the carbon-carbon double bond contained in the polybutadiene. In a trans-bond configuration, the main internal polymer chain is on opposite sides of the internal carbon-carbon double bond in the polybutadiene. The polybutadiene rubber can have various combinations of cis- and trans-bond structures. A preferred polybutadiene rubber has a 1,4 cis-bond content of at least 40%, preferably greater than 80%, and more preferably greater than 90%. In general, highly crosslinked polybutadiene rubbers having a high 1,4 cis-bond content have high tensile strength. The polybutadiene rubber may have a relatively high or low Mooney viscosity.

Examples of commercially available polybutadiene base rubbers that can be used in accordance with this invention, include, but are not limited to, BR 01 and BR 1220, available from BST Elastomers of Bangkok, Thailand; SE BR 1220LA and SE BR1203, available from DOW Chemical Co of Midland, Mich.; BUDENE 1207, 1207s, 1208, and 1280 available from Goodyear, Inc of Akron, Ohio; BR 01, 51 and 730, available from Japan Synthetic Rubber (JSR) of Tokyo, Japan; BUNA CB 21, CB 22, CB 23, CB 24, CB 25, CB 29 MES, CB 60, CB Nd 60, CB 55 NF, CB 70 B, CB KA 8967, and CB 1221, available from Lanxess Corp. of Pittsburgh. Pa.; BR1208, available from LG Chemical of Seoul, South Korea; UBEPOL BR130B, BR150, BR150B, BR150L, BR230, BR360L, BR710, and VCR617, available from UBE Industries, Ltd. of Tokyo, Japan; EUROPRENE NEOCIS BR 60, INTENE 60 AF and P30AF, and EUROPRENE BR HV80, available from Polimeri Europa of Rome, Italy; AFDENE 50 and NEODENE BR40, BR45, BR50 and BR60, available from Karbochem (PTY) Ltd. of Bruma, South Africa; KBR 01, NdBr 40, NdBR-45, NdBr 60, KBR 710S, KBR 710H, and KBR 750, available from Kumho Petrochemical Co., Ltd. Of Seoul, South Korea; DIENE 55NF, 70AC, and 320 AC, available from Firestone Polymers of Akron, Ohio; and PBR-Nd Group II and Group III, available from Nizhnekamskneftekhim, Inc. of Nizhnekamsk, Tartarstan Republic.

Other suitable polybutadiene base rubbers include BUNA® CB22, BUNA® CB23 and BUNA® CB24, BUNA 1203G1, 1220, 1221, and BUNA CBNd-40, commercially available from LANXESS Corporation; BSTE BR-1220 available from BST Elastomers Co. LTD; UBEPOL® 360L and UBEPOL® 150L and UBEPOL-BR rubbers, commercially available from UBE Industries, Ltd. of Tokyo, Japan; Budene 1207, 1208 and 1280, commercially available from Goodyear of Akron, Ohio; SE BR-1220, commercially available from Dow Chemical Company; Europrene® NEOCIS® BR 40 and BR 60, commercially available from Polimeri Europa; and BR 01, BR 730, BR 735, BR 11, and BR 51, commercially available from Japan Synthetic Rubber Co., Ltd; and NEODENE 40, 45, and 60, commercially available from Karbochem.

Still other suitable base rubbers may include polyisoprene rubber, natural rubber, ethylene-propylene rubber, ethylene-propylene diene rubber, styrene-butadiene rubber, and combinations of two or more thereof. Another preferred base rubber is polybutadiene optionally mixed with one or more elastomers such as polyisoprene rubber, natural rubber, ethylene propylene rubber, ethylene propylene diene rubber, styrene-butadiene rubber, polystyrene elastomers, polyethylene elastomers, polyurethane elastomers, polyurea elastomers, acrylate rubbers, polyocteriamers, metallocene-catalyzed elastomers, and plastomers. As discussed further below, highly neutralized acid copolymers (HNPs), as known in the art, also can be used to form the core layer as part of the blend. Such compositions will provide increased flexural modulus and toughness thereby improving the golf ball's performance including its impact durability.

The base rubbers may be blended with each other and typically may be mixed with at least one reactive cross-linking co-agent to enhance the hardness of the rubber composition. Suitable co-agents include, but are not limited to, unsaturated carboxylic acids and unsaturated vinyl compounds. A preferred unsaturated vinyl compound is trimethylolpropane trimethacrylate. The rubber composition is cured using a conventional curing process. Suitable curing processes include, for example, peroxide curing, sulfur curing, high-energy radiation, and combinations thereof. In one embodiment, the base rubber is peroxide cured. Organic peroxides suitable as free-radical initiators include, for example, dicumyl peroxide; n-butyl-4,4-di(t-butylperoxy)valerate; 1,1-di(t-butylperoxy)3,3,5-trimethylcyclohexane; 2,5-dimethyl-2,5-di(t-butylperoxy)hexane; di-t-butyl peroxide; di-t-amyl peroxide; t-butyl peroxide; t-butyl cumyl peroxide; 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3; di(2-t-butyl-peroxyisopropyl)benzene; dilauroyl peroxide; dibenzoyl peroxide; t-butyl hydroperoxide; and combinations thereof. Cross-linking co-agents are used to cross-link at least a portion of the polymer chains in the composition. Suitable cross-linking co-agents include, for example, metal salts of unsaturated carboxylic acids having from 3 to 8 carbon atoms; unsaturated vinyl compounds and polyfunctional monomers (for example, trimethylolpropane trimethacrylate); phenylene bismaleimide; and combinations thereof. In a particular embodiment, the cross-linking co-agent is selected from zinc salts of acrylates, diacrylates, methacrylates, and dimethacrylates. In another particular embodiment, the cross-linking co-agent is zinc diacrylate (“ZDA”). Commercially available zinc diacrylates include those selected from Cray Valley or Resource Innovations Inc. Other elastomers known in the art may also be added, such as other polybutadiene rubbers, natural rubber, styrene butadiene rubber, and/or isoprene rubber in order to further modify the properties of the core. When a mixture of elastomers is used, the amounts of other constituents in the core composition are typically based on 100 parts by weight of the total elastomer mixture.

Thermoplastic elastomers (TPE) may also be used to modify the properties of the core layers, or the uncured core layer stock by blending with the uncured rubber. These TPEs include natural or synthetic balata, or high trans-polyisoprene, high trans-polybutadiene, or any styrenic block copolymer, such as styrene ethylene butadiene styrene, styrene-isoprene-styrene, etc., a metallocene or other single-site catalyzed polyolefin such as ethylene-octene, or ethylene-butene, or thermoplastic polyurethanes (TPU), including copolymers, e.g. with silicone. Other suitable TPEs for blending with the thermoset rubbers of the present invention include PEBAX®, which is believed to comprise polyether amide copolymers, HYTREL®, which is believed to comprise polyether ester copolymers, thermoplastic urethane, and KRATON®, which is believed to comprise styrenic block copolymer elastomers. Any of the TPEs or TPUs above may also contain functionality suitable for grafting, including maleic acid or maleic anhydride. Any of the Thermoplastic Vulcanized Rubbers (TPV) such as Santoprene® or Vibram® or ETPV® can be used along with a present invention. In one embodiment, the TPV has a thermoplastic as a continuous phase and a cross-linked rubber particulate as a dispersed (or discontinuous) phase. In another embodiment, the TPV has a cross-linked phase as a continuous phase and a thermoplastic as a dispersed (or discontinuous) phase to provide reduced loss in elasticity in order to improve the resiliency of the golf ball.

The rubber compositions also may contain “soft and fast” agents such as a halogenated organosulfur, organic disulfide, or inorganic disulfide compounds. Particularly suitable halogenated organosulfur compounds include, but are not limited to, halogenated thiophenols. Preferred organic sulfur compounds include, but not limited to, pentachlorothiophenol (“PCTP”) and a salt of PCTP. A preferred salt of PCTP is ZnPCTP. A suitable PCTP is sold by the Struktol Company (Stow, Ohio) under the tradename, A95. ZnPCTP is commercially available from EchinaChem (San Francisco, Calif.). These compounds also may function as cis-to-trans catalysts to convert some cis bonds in the polybutadiene to trans bonds. Antioxidants also may be added to the rubber compositions to prevent the breakdown of the elastomers. Other ingredients such as accelerators (for example, tetramethylthiuram sulfides), processing aids, dyes and pigments, wetting agents, surfactants, plasticizers, as well as other additives known in the art may be added to the rubber composition.

The core may be formed by mixing and forming the rubber composition using conventional techniques. These cores can be used to make finished golf balls by surrounding the core with outer core layer(s), intermediate layer(s), and/or cover materials as discussed further below. In another embodiment, the cores can be formed using highly neutralized polymer (HNP) compositions as disclosed in U.S. Pat. Nos. 6,756,436, 7,030,192, 7,402,629, and 7,517,289. The cores from the highly neutralized polymer compositions can be further cross-linked using any free-radical initiation sources including radiation sources such as gamma or electron beam as well as chemical sources such as peroxides and the like.

Golf balls made in accordance with this invention can be of any size, although the USGA requires that golf balls used in competition have a diameter of at least 1.68 inches and a weight of no greater than 1.62 ounces. For play outside of USGA competition, the golf balls can have smaller diameters and be heavier.

A wide variety of thermoplastic or thermosetting materials can be employed in forming the center, core layer(s), intermediate layer(s), and/or cover layer(s). These materials include for example, grafted polyolefins such as Fusabond®525D or olefin-based copolymer ionomer resins for example, Surlyn® ionomer resins and DuPont® HPF 1000 and HPF 2000, as well as blends of Surlyn®7940/Surlyn®8940 or Surlyn®8150/Surlyn®9150, all commercially available from E.I. du Pont de Nemours and Company; Iotek® ionomers, commercially available from ExxonMobil Chemical Company; Amplify® IO ionomers of ethylene acrylic acid copolymers, commercially available from The Dow Chemical Company; and Clarix® ionomer resins, commercially available from A. Schulman Inc.; polyurethanes; polyureas; copolymers and hybrids of polyurethane and polyurea; polyethylene, including, for example, low density polyethylene, linear low density polyethylene, and high density polyethylene; polypropylene; rubber-toughened olefin polymers; acid polymers, for example, poly(meth)acrylic acid, which do not become part of an ionomeric copolymer; plastomers; flexomers; styrene-butadiene-styrene block copolymers; styrene-ethylene-butylene-styrene block copolymers; dynamically vulcanized elastomers; copolymers of ethylene and vinyl acetates; copolymers of ethylene and methyl acrylates; polyvinyl chloride resins; polyamides, poly(amide-ester) elastomers, and graft copolymers of ionomer and polyamide including, for example, Pebax® thermoplastic polyether block amides, commercially available from Arkema Inc; cross-linked trans-polyisoprene and blends thereof; polyester-based thermoplastic elastomers, such as Hytrel®, commercially available from E.I. du Pont de Nemours and Company; polyurethane-based thermoplastic elastomers, such as Elastollan®, commercially available from BASF; synthetic or natural vulcanized rubber; and combinations thereof.

In fact, any of the core, intermediate layer and/or cover layers may include the following materials:

(1) Polyurethanes, such as those prepared from polyols and diisocyanates or polyisocyanates and/or their prepolymers;

(2) Polyureas; and

(3) Polyurethane-urea hybrids, blends or copolymers comprising urethane and urea segments.

Suitable polyurethane compositions comprise a reaction product of at least one polyisocyanate and at least one curing agent. The curing agent can include, for example, one or more polyamines, one or more polyols, or a combination thereof. The polyisocyanate can be combined with one or more polyols to form a prepolymer, which is then combined with the at least one curing agent. Thus, the polyols described herein are suitable for use in one or both components of the polyurethane material, i.e., as part of a prepolymer and in the curing agent. Suitable polyurethanes are described in U.S. Patent Application Publication No. 2005/0176523, which is incorporated by reference in its entirety.

Any polyisocyanate available to one of ordinary skill in the art is suitable for use according to the invention. Exemplary polyisocyanates include, but are not limited to, 4,4′-diphenylmethane diisocyanate (MDI); polymeric MDI; carbodiimide-modified liquid MDI; 4,4′-dicyclohexylmethane diisocyanate (H₁₂MDI); p-phenylene diisocyanate (PPDI); m-phenylene diisocyanate (MPDI); toluene diisocyanate (TDI); 3,3′-dimethyl-4,4′-biphenylene diisocyanate; isophoronediisocyanate; 1,6-hexamethylene diisocyanate (HDI); naphthalene diisocyanate; xylene diisocyanate; p-tetramethylxylene diisocyanate; m-tetramethylxylene diisocyanate; ethylene diisocyanate; propylene-1,2-diisocyanate; tetramethylene-1,4-diisocyanate; cyclohexyl diisocyanate; dodecane-1,12-diisocyanate; cyclobutane-1,3-diisocyanate; cyclohexane-1,3-diisocyanate; cyclohexane-1,4-diisocyanate; 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane; methyl cyclohexylene diisocyanate; triisocyanate of HDI; triisocyanate of 2,4,4-trimethyl-1,6-hexane diisocyanate; tetracene diisocyanate; napthalene diisocyanate; anthracene diisocyanate; isocyanurate of toluene diisocyanate; uretdione of hexamethylene diisocyanate, homopolymers, dimers, trimers and mixtures thereof. Polyisocyanates are known to those of ordinary skill in the art as having more than one isocyanate group, e.g., di-isocyanate, tri-isocyanate, and tetra-isocyanate. Preferably, the polyisocyanate includes MDI, PPDI, TDI, or a mixture thereof, and more preferably, the polyisocyanate includes MDI. It should be understood that, as used herein, the term MDI includes 4,4′-diphenylmethane diisocyanate, polymeric MDI, carbodiimide-modified liquid MDI, and mixtures thereof. Additionally, the prepolymers synthesized from these diisocyanates may be “low free monomer,” understood by one of ordinary skill in the art to have lower levels of “free” isocyanate monomers, typically less than about 0.1% free isocyanate. Examples of “low free monomer” prepolymers include, but are not limited to Low Free Monomer MDI prepolymers, Low Free Monomer TDI prepolymers, and Low Free Monomer PPDI prepolymers.

Any polyol available to one of ordinary skill in the art is suitable for use according to the invention. Exemplary polyols include, but are not limited to, polyether polyols, hydroxy-terminated polybutadiene (including partially/fully hydrogenated derivatives), polyester polyols, polycaprolactone polyols, and polycarbonate polyols. In one preferred embodiment, the polyol includes polyether polyol. Examples include, but are not limited to, polytetramethylene ether glycol (PTMEG), polyethylene propylene glycol, polyoxypropylene glycol, and mixtures thereof. The hydrocarbon chain can have saturated or unsaturated bonds and substituted or unsubstituted aromatic and cyclic groups. Preferably, the polyol of the present invention includes PTMEG.

In another embodiment, polyester polyols are included in the polyurethane material. Suitable polyester polyols include, but are not limited to, polyethylene adipate glycol; polybutylene adipate glycol; polyethylene propylene adipate glycol; o-phthalate-1,6-hexanediol; poly(hexamethylene adipate)glycol; and mixtures thereof. The hydrocarbon chain can have saturated or unsaturated bonds, or substituted or unsubstituted aromatic and cyclic groups.

In another embodiment, polycaprolactone polyols are included in the materials of the invention. Suitable polycaprolactone polyols include, but are not limited to, 1,6-hexanediol-initiated polycaprolactone, diethylene glycol initiated polycaprolactone, trimethylol propane initiated polycaprolactone, neopentyl glycol initiated polycaprolactone, 1,4-butanediol-initiated polycaprolactone, and mixtures thereof. The hydrocarbon chain can have saturated or unsaturated bonds, or substituted or unsubstituted aromatic and cyclic groups.

In yet another embodiment, polycarbonate polyols are included in the polyurethane material of the invention. Suitable polycarbonates include, but are not limited to, polyphthalate carbonate and poly(hexamethylene carbonate)glycol. The hydrocarbon chain can have saturated or unsaturated bonds, or substituted or unsubstituted aromatic and cyclic groups. In one embodiment, the molecular weight of the polyol is from about 200 to about 4000.

Polyamine curatives are also suitable for use in the polyurethane composition of the invention and have been found to improve cut, shear, and impact resistance of the resultant balls. Preferred polyamine curatives include, but are not limited to, 3,5-dimethylthio-2,4-toluenediamine and isomers thereof; 3,5-diethyltoluene-2,4-diamine and isomers thereof, such as 3,5-diethyltoluene-2,6-diamine; 4,4′-bis-(sec-butylamino)-diphenylmethane; 1,4-bis-(sec-butylamino)-benzene, 4,4′-methylene-bis-(2-chloroaniline); 4,4′-methylene-bis-(3-chloro-2,6-diethylaniline); polytetramethyleneoxide-di-p-aminobenzoate; N,N′-dialkyldiamino diphenyl methane; p,p′-methylene dianiline; m-phenylenediamine; 4,4′-methylene-bis-(2-chloroaniline); 4,4′-methylene-bis-(2,6-diethylaniline); 4,4′-methylene-bis-(2,3-dichloroaniline); 4,4′-diamino-3,3′-diethyl-5,5′-dimethyl diphenylmethane; 2,2′,3,3′-tetrachloro diamino diphenylmethane; trimethylene glycol di-p-aminobenzoate; and mixtures thereof. Preferably, the curing agent of the present invention includes 3,5-dimethylthio-2,4-toluenediamine and isomers thereof, such as ETHACURE® 300, commercially available from Albermarle Corporation of Baton Rouge, La. Suitable polyamine curatives, which include both primary and secondary amines, preferably have molecular weights ranging from about 64 to about 2000.

At least one of a diol, triol, tetraol, or hydroxy-terminated curatives may be added to the aforementioned polyurethane composition. Suitable diol, triol, and tetraol groups include ethylene glycol; diethylene glycol; polyethylene glycol; propylene glycol; polypropylene glycol; lower molecular weight polytetramethylene ether glycol; 1,3-bis(2-hydroxyethoxy)benzene; 1,3-bis-[2-(2-hydroxyethoxy)ethoxy]benzene; 1,3-bis-{2-[2-(2-hydroxyethoxy)ethoxy]ethoxy}benzene; 1,4-butanediol; 1,5-pentanediol; 1,6-hexanediol; resorcinol-di-(β-hydroxyethyl)ether; hydroquinone-di-(β-hydroxyethyl)ether; and mixtures thereof. Preferred hydroxy-terminated curatives include 1,3-bis(2-hydroxyethoxy)benzene; 1,3-bis-[2-(2-hydroxyethoxy)ethoxy]benzene; 1,3-bis-{2-[2-(2-hydroxyethoxy)ethoxy]ethoxy}benzene; 1,4-butanediol, and mixtures thereof. Preferably, the hydroxy-terminated curatives have molecular weights ranging from about 48 to 2000. It should be understood that molecular weight, as used herein, is the absolute weight average molecular weight and would be understood as such by one of ordinary skill in the art.

Both the hydroxy-terminated and amine curatives can include one or more saturated, unsaturated, aromatic, and cyclic groups. Additionally, the hydroxy-terminated and amine curatives can include one or more halogen groups. The polyurethane composition can be formed with a blend or mixture of curing agents. If desired, however, the polyurethane composition may be formed with a single curing agent.

In one embodiment of the present invention, saturated polyurethanes are used to form one or more of the cover layers. Additionally, polyurethane can be replaced with or blended with a polyurea material.

The polyether amine may be blended with additional polyols to formulate copolymers that are reacted with excess isocyanate to form a prepolymer. In one embodiment, less than about 30 percent polyol by weight of the copolymer is blended with the saturated polyether amine. In another embodiment, less than about 20 percent polyol by weight of the copolymer, preferably less than about 15 percent by weight of the copolymer, is blended with the polyether amine. The polyols listed above with respect to the polyurethane prepolymer, e.g., polyether polyols, polycaprolactone polyols, polyester polyols, polycarbonate polyols, hydrocarbon polyols, other polyols, and mixtures thereof, are also suitable for blending with the polyether amine. The molecular weight of these polymers may be from about 200 to about 4000, but also may be from about 1000 to about 3000, and more preferably are from about 1500 to about 2500.

The polyurea composition can be formed by crosslinking a polyurea prepolymer with a single curing agent or a blend of curing agents. In one embodiment, the amine-terminated curing agent may have a molecular weight of about 64 or greater. In another embodiment, the molecular weight of the amine-curing agent is about 2000 or less. As discussed above, certain amine-terminated curing agents may be modified with a compatible amine-terminated freezing point depressing agent or mixture of compatible freezing point depressing agents

Suitable amine-terminated curing agents include, but are not limited to, ethylene diamine; hexamethylene diamine; 1-methyl-2,6-cyclohexyl diamine; tetrahydroxypropylene ethylene diamine; 2,2,4- and 2,4,4-trimethyl-1,6-hexanediamine; 4,4′-bis-(sec-butylamino)-dicyclohexylmethane; 1,4-bis-(sec-butylamino)-cyclohexane; 1,2-bis-(sec-butylamino)-cyclohexane; derivatives of 4,4′-bis-(sec-butylamino)-dicyclohexylmethane; 4,4′-dicyclohexylmethane diamine; 1,4-cyclohexane-bis-(methylamine); 1,3-cyclohexane-bis-(methylamine); diethylene glycol di-(aminopropyl)ether; 2-methylpentamethylene-diamine; diaminocyclohexane; diethylene triamine; triethylene tetramine; tetraethylene pentamine; propylene diamine; 1,3-diaminopropane; dimethylamino propylamine; diethylamino propylamine; dipropylene triamine; imido-bis-propylamine; monoethanolamine, diethanolamine; 3,5-diethyltoluene-2,4-diamine; triethanolamine; monoisopropanolamine, diisopropanolamine; isophoronediamine; 4,4′-methylenebis-(2-chloroaniline); 3,5-dimethylthio-2,4-toluenediamine; 3,5-dimethylthio-2,6-toluenediamine; 3,5-diethylthio-2,4-toluenediamine; 3,5-diethylthio-2,6-toluenediamine; 4,4′-bis-(sec-butylamino)-diphenylmethane and derivatives thereof; 1,4-bis-(sec-butylamino)-benzene; 1,2-bis-(sec-butylamino)-benzene; N,N′-dialkylamino-diphenylmethane; N,N,N′,N′-tetrakis(2-hydroxypropyl)ethylene diamine; trimethyleneglycol-di-p-aminobenzoate; polytetramethyleneoxide-di-p-aminobenzoate; 4,4′-methylenebis-(3-chloro-2,6-diethyleneaniline); 4,4′-methylenebis-(2,6-diethylaniline); meta-phenylenediamine; paraphenylenediamine; and mixtures thereof. In one embodiment, the amine-terminated curing agent is 4,4′-bis-(sec-butylamino)-dicyclohexylmethane.

Suitable saturated amine-terminated curing agents include, but are not limited to, ethylene diamine; hexamethylene diamine; 1-methyl-2,6-cyclohexyl diamine; tetrahydroxypropylene ethylene diamine; 2,2,4- and 2,4,4-trimethyl-1,6-hexanediamine; 4,4′-bis-(sec-butylamino)-dicyclohexylmethane; 1,4-bis-(sec-butylamino)-cyclohexane; 1,2-bis-(sec-butylamino)-cyclohexane; derivatives of 4,4′-bis-(sec-butylamino)-dicyclohexylmethane; 4,4′-dicyclohexylmethane diamine; 4,4′-methylenebis-(2,6-diethylaminocyclohexane; 1,4-cyclohexane-bis-(methylamine); 1,3-cyclohexane-bis-(methylamine); diethylene glycol di-(aminopropyl)ether; 2-methylpentamethylene-diamine; diaminocyclohexane; diethylene triamine; triethylene tetramine; tetraethylene pentamine; propylene diamine; 1,3-diaminopropane; dimethylamino propylamine; diethylamino propylamine; imido-bis-propylamine; monoethanolamine, diethanolamine; triethanolamine; monoisopropanolamine, diisopropanolamine; isophoronediamine; triisopropanolamine; and mixtures thereof. In addition, any of the polyether amines listed above may be used as curing agents to react with the polyurea prepolymers.

Suitable UV absorbers/light stabilizers may be incorporated including but not limited to triazines; benzoxazinones; benzotriazoles; poly-(oxy-1,2-ethanediyl)-α-(3-(3-(2H-benzotriazol-2-yl)-5-(1,1-dimethylethyl)-4-hydroxyphenyl)-1-oxopropyl)-ω-hydroxy or 2-(2H-benzotriazol-2-yl)-4,6-bis-(1,1-dimethylpropyl)-phenol; dimethyliones; benzimidazoles; cycloaliphatic ketones; formanilides; cyanoacrylates; benzopyranones; succinate polymer with 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol; bis-(1,2,2,6,6-pentamethyl-4-piperidinyl)sebacate; bis-(2,2,6,6-tetramethyl-4-piperidinyl)sebacate; benzophenones; benzoates; formamidines; cinnamates/propenoates; aromatic propanediones, and mixtures thereof.

Alternatively, other suitable polymers include partially or fully neutralized ionomer, metallocene, or other single-site catalyzed polymer, polyester, polyamide, non-ionomeric thermoplastic elastomer, copolyether-esters, copolyether-amides, polycarbonate, polybutadiene, polyisoprene, polystryrene block copolymers (such as styrene-butadiene-styrene), styrene-ethylene-propylene-styrene, styrene-ethylene-butylene-styrene, and the like, and blends thereof.

Intermediate layers and/or cover layers may also be formed from ionomeric polymers or ionomer blends such as Surlyn 7940/8940 or Surlyn 8150/9150 or from highly-neutralized ionomers (HNP).

In one embodiment, at least one intermediate layer of the golf ball is formed from an HNP material or a blend of HNP materials. The acid moieties of the HNP's, typically ethylene-based ionomers, are preferably neutralized greater than about 70%, more preferably greater than about 90%, and most preferably at least about 100% with a cation source. Suitable cations include for example metal cations, organic amine compounds, ammonium, and combinations thereof. The HNPs can be also be blended with a second polymer component, which, if containing an acid group(s) such as organic acids, or more preferably fatty acids, may be neutralized in a conventional manner, with a suitable cation source. The second polymer component, which may be partially or fully neutralized, preferably comprises ionomeric copolymers and terpolymers, ionomer precursors, thermoplastics, polyamides, polycarbonates, polyesters, polyurethanes, polyureas, thermoplastic elastomers, polybutadiene rubber, balata, metallocene-catalyzed polymers (grafted and non-grafted), single-site polymers, high-crystalline acid polymers, cationic ionomers, and the like. HNP polymers typically have a material hardness of between about 20 and about 80 Shore D, and a flexural modulus of between about 3,000 psi and about 200,000 psi.

In one embodiment of the present invention the HNPs are ionomers and/or their acid precursors that are preferably neutralized, either fully or partially, with sufficient amount of metal base to achieve the desired neutralization level. The acid copolymers are preferably α-olefin, such as ethylene, C₃₋₈ α,β-ethylenically unsaturated carboxylic acid, such as acrylic and methacrylic acid, copolymers. They may optionally contain a softening monomer, such as alkyl acrylate and alkyl methacrylate, wherein the alkyl groups have from 1 to 8 carbon atoms.

The acid copolymers can be described as E/X/Y copolymers where E is ethylene, X is an α,β-ethylenically unsaturated carboxylic acid, and Y is a softening comonomer. In a preferred embodiment, X is acrylic or methacrylic acid and Y is a C₁₋₈ alkyl acrylate or methacrylate ester. X is preferably present in an amount from about 1 to about 35 weight percent of the polymer, more preferably from about 5 to about 30 weight percent of the polymer, and most preferably from about 10 to about 22 weight percent of the polymer. Y is preferably present in an amount from about 0 to about 50 weight percent of the polymer, more preferably from about 5 to about 30 weight percent of the polymer, and most preferably from about 10 to about 25 weight percent of the polymer.

Specific acid-containing ethylene copolymers include, but are not limited to, ethylene/acrylic acid/n-butyl acrylate, ethylene/methacrylic acid/n-butyl acrylate, ethylene/methacrylic acid/iso-butyl acrylate, ethylene/acrylic acid/iso-butyl acrylate, ethylene/methacrylic acid/n-butyl methacrylate, ethylene/acrylic acid/methyl methacrylate, ethylene/acrylic acid/methyl acrylate, ethylene/methacrylic acid/methyl acrylate, ethylene/methacrylic acid/methyl methacrylate, and ethylene/acrylic acid/n-butyl methacrylate. Preferred acid-containing ethylene copolymers include, ethylene/methacrylic acid/n-butyl acrylate, ethylene/acrylic acid/n-butyl acrylate, ethylene/methacrylic acid/methyl acrylate, ethylene/acrylic acid/ethyl acrylate, ethylene/methacrylic acid/ethyl acrylate, and ethylene/acrylic acid/methyl acrylate copolymers. The most preferred acid-containing ethylene copolymers are, ethylene/(meth)acrylic acid/n-butyl acrylate, ethylene/(meth)acrylic acid/ethyl acrylate, and ethylene/(meth)acrylic acid/methyl acrylate copolymers.

Ionomers are typically neutralized with a metal cation, such as Li, Na, Mg, K, Ca, Al or Zn. It has been found that by adding sufficient organic acid or salt of organic acid, along with a suitable base, to the acid copolymer or ionomer, the ionomer can be neutralized, without losing processability, to a level much greater than for a metal cation alone. Preferably, the acid moieties are neutralized greater than about 80%, preferably from 90-100%, most preferably 100% without losing processability. This is accomplished by melt-blending an ethylene α,β-ethylenically unsaturated carboxylic acid copolymer, for example, with an organic acid or a salt of organic acid, and adding a sufficient amount of a cation source to increase the level of neutralization of all the acid moieties (including those in the acid copolymer and in the organic acid) to greater than 90%, (preferably greater than 100%).

The organic acids may be aliphatic, mono- or multi-functional (saturated, unsaturated, or multi-unsaturated) organic acids. Salts of these organic acids may also be employed. The salts of organic acids of the present invention include the salts of barium, lithium, sodium, zinc, bismuth, chromium, cobalt, copper, potassium, strontium, titanium, tungsten, magnesium, cesium, iron, nickel, silver, aluminum, tin, or calcium, salts of fatty acids, particularly stearic, behenic, erucic, oleic, linoelic or dimerized derivatives thereof. It is preferred that the organic acids and salts of the present invention be relatively non-migratory (they do not bloom to the surface of the polymer under ambient temperatures) and non-volatile (they do not volatilize at temperatures required for melt-blending).

The ionomers may also be more conventional ionomers, i.e., partially-neutralized with metal cations. The acid moiety in the acid copolymer is neutralized about 1 to about 90%, preferably at least about 20 to about 75%, and more preferably at least about 40 to about 70%, to form an ionomer, by a cation such as lithium, sodium, potassium, magnesium, calcium, barium, lead, tin, zinc, aluminum, or a mixture thereof.

The golf ball may also contain additives, ingredients, and other materials in amounts that do not detract from the properties of the final composition. These additive materials include, but are not limited to, activators such as calcium or magnesium oxide; fatty acids such as stearic acid and salts thereof; fillers and reinforcing agents such as organic or inorganic particles, for example, clays, talc, calcium, magnesium carbonate, silica, aluminum silicates, zeolites, powdered metals, and organic or inorganic fibers, plasticizers such as dialkyl esters of dicarboxylic acids; surfactants; softeners; tackifiers; waxes; ultraviolet (UV) light absorbers and stabilizers; antioxidants; optical brighteners; whitening agents such as titanium dioxide and zinc oxide; dyes and pigments; processing aids; release agents; and wetting agents. These compositions provide improved melt processability, and a balance of ball performance.

Blowing/foaming agents may also be compatible with and be included in golf balls of the invention, including, for example those disclosed in U.S. Pat. No. 7,708,654. Typical physical foaming/blowing agents include volatile liquids such as freons (CFCs), other halogenated hydrocarbons, water, aliphatic hydrocarbons, gases, and solid blowing agents, i.e., compounds that liberate gas as a result of desorption of gas. Preferably, the blowing agent includes an adsorbent. Typical adsorbents include, for example, activated carbon, calcium carbonate, diatomaceous earth, and silicates saturated with carbon dioxide.

Chemical foaming/blowing agents may be incorporated. Chemical blowing agents may be inorganic, such as ammonium carbonate and carbonates of alkalai metals, or may be organic, such as azo and diazo compounds, such as nitrogen-based azo compounds. Suitable azo compounds include, but are not limited to, 2,2′-azobis(2-cyanobutane), 2,2′-azobis(methylbutyronitrile), azodicarbonamide, p,p′-oxybis(benzene sulfonyl hydrazide), p-toluene sulfonyl semicarbazide, p-toluene sulfonyl hydrazide. Other blowing agents include any of the Celogens®, sold by Crompton Chemical Corporation, and nitroso compounds, sulfonylhydrazides, azides of organic acids and their analogs, triazines, tri- and tetrazole derivatives, sulfonyl semicarbazides, urea derivatives, guanidine derivatives, and esters such as alkoxyboroxines. Other possible blowing agents include agents that liberate gasses as a result of chemical interaction between components such as mixtures of acids and metals, mixtures of organic acids and inorganic carbonates, mixtures of nitriles and ammonium salts, and the hydrolytic decomposition of urea.

Alternatively, low specific gravity can be achieved by incorporating low density fillers or agents such as hollow fillers or microspheres in the polymeric matrix, where the cured composition has the preferred specific gravity. Moreover, the polymeric matrix can be foamed to decrease its specific gravity, microballoons, or other low density fillers as described in U.S. Pat. No. 6,692,380 (“'380 patent”). The '380 patent is incorporated by reference in its entirety.

Blends including non-ionomeric and olefin-based ionomeric polymers may also be incorporated to form a golf ball layer. Examples of non-ionomeric polymers include vinyl resins, polyolefins including those produced using a single-site catalyst or a metallocene catalyst, polyurethanes, polyureas, polyamides, polyphenylenes, polycarbonates, polyesters, polyacrylates, engineering thermoplastics, and the like. Also, in one embodiment of the invention, processability of the golf ball of the invention may even be enhanced by incorporating in the core a metallocene-catalyzed polybutadiene.

Olefin-based ionomers, such as ethylene-based copolymers, are often made from an unsaturated carboxylic acid, such as methacrylic acid, acrylic acid, or maleic acid. Other possible carboxylic acid groups include, for example, crotonic, maleic, fumaric, and itaconic acid. “Low acid” and “high acid” olefin-based ionomers, as well as blends of such ionomers, may be used. In general, low acid ionomers are considered to be those containing 16 wt. % or less of carboxylic acid, whereas high acid ionomers are considered to be those containing greater than 16 wt. % of carboxylic acid. The acidic group in the olefin-based ionic copolymer is partially or totally neutralized with metal ions such as zinc, sodium, lithium, magnesium, potassium, calcium, manganese, nickel, chromium, copper, or a combination thereof. For example, ionomeric resins having carboxylic acid groups that are neutralized from about 10 percent to about 100 percent may be used. In one embodiment, the acid groups are partially neutralized. That is, the neutralization level is from 10 to 80%, more preferably 20 to 70%, and most preferably 30 to 50%. In another embodiment, the acid groups are highly or fully neutralized. Or, the neutralization level may be from about 80 to 100%, more preferably 90 to 100%, and most preferably 95 to 100%. The blend may contain about 5 to about 30% by weight of a moisture barrier composition and about 95 to about 70% by weight of a partially, highly, or fully-neutralized olefin-based ionomeric copolymer. The above-mentioned blends may contain one or more suitable compatibilizers such as glycidyl acrylate or glycidyl methacrylate or maleic anhydride containing-polymers.

Any method known in the art for measuring neutralization, hardness, modulus and melt flow of golf ball centers and layers may be used.

A golf ball of the invention may have a compression of from about 25 to about 110. In another embodiment, the overall golf ball has a compression of from about 35 to about 100. In yet another embodiment, the overall golf ball has a compression of from about 45 to about 95. In still another embodiment, the compression may be from about 55 to about 85, or from about 65 to about 75. Meanwhile, the compression may also be from about 50 to about 110, or from about 60 to about 100, or from about 70 to about 90, or even from about 80 to about 110.

Several different methods can be used to measure compression, including Atti compression, Riehle compression, load/deflection measurements at a variety of fixed loads and offsets, and effective modulus. See, e.g., Compression by Any Other Name, Science and Golf IV, Proceedings of the World Scientific Congress of Golf (Eric Thain ed., Routledge, 2002) (“J. Dalton”) The term compression, as used herein, refers to Atti or PGA compression and is measured using an Atti compression test device. A piston compresses a ball against a spring and the piston remains fixed while deflection of the spring is measured at 1.25 mm (0.05 inches). Where a core has a very low stiffness, the compression measurement will be zero at 1.25 mm. In order to measure the compression of a core using an Atti compression tester, the core must be shimmed to a diameter of 1.680 inches because these testers are designed to measure objects having that diameter. Atti compression units can be converted to Riehle (cores), Riehle (balls), 100 kg deflection, 130-10 kg deflection or effective modulus using the formulas set forth in J. Dalton. The approximate relationship that exists between Atti or PGA compression and Riehle compression can be expressed as: (Atti or PGA compression)=(160-Riehle Compression). Thus, a Riehle compression of 100 would be the same as an Atti compression of 60.

Generally, in golf balls of the invention, the overall golf ball COR is at least about 0.780. In another embodiment, the overall golf ball COR is at least about 0.788. In yet another embodiment, the overall golf ball COR is at least about 0.791. In still another embodiment, the overall golf ball COR is at least about 0.794. Also, the overall golf ball COR may be at least about 0.797. The overall golf ball COR may even be at least about 0.800, or at least about 0.803, or at least about 0.812.

COR, as used herein, is determined by firing a golf ball or golf ball subassembly (e.g., a golf ball core) from an air cannon at two given velocities and calculating the COR at a velocity of 125 ft/s. Ball velocity is calculated as a ball approaches ballistic light screens which are located between the air cannon and a steel plate at a fixed distance. As the ball travels toward the steel plate, each light screen is activated, and the time at each light screen is measured. This provides an incoming transit time period inversely proportional to the ball's incoming velocity. The ball impacts the steel plate and rebounds through the light screens, which again measure the time period required to transit between the light screens. This provides an outgoing transit time period inversely proportional to the ball's outgoing velocity. COR is then calculated as the ratio of the outgoing transit time period to the incoming transit time period, COR=V_(out)/V_(in)=T_(in)/T_(out). Preferably, a golf ball according to the present invention has a COR of at least about 0.78, more preferably, at least about 0.80.

The spin rate of a golf ball also remains an important golf ball characteristic. High spin rate allows skilled players more flexibility in stopping the ball on the green if they are able to control a high spin ball. On the other hand, recreational players often prefer a low spin ball since they do not have the ability to intentionally control the ball, and lower spin balls tend to drift less off the green.

Golf ball spin is dependent on variables including, for example, distribution of the density or specific gravity within a golf ball. For example, when the center has a higher density or specific gravity than the outer layers, a lower moment of inertia results which increases spin rate. Alternatively, when the density or specific gravity is concentrated in the outer regions of the golf ball, a higher moment of inertia results with a lower spin rate. The moment of inertia for a golf ball of the invention may be from about 0.410 oz-in² to about 0.470 oz-in². The moment of inertia for a one piece ball that is 1.62 ounces and 1.68 inches in diameter may be approximately 0.4572 oz-in², which is the baseline moment of inertia value. Accordingly, by varying the materials and the density of the regions of each core or cover layer, different moments of inertia may be achieved for the golf ball of the present invention. In one embodiment, the resulting golf ball has a moment of inertia of from about to 0.440 to about 0.455 oz-in². In another embodiment, the golf balls of the present invention have a moment of inertia of from about 0.456 oz-in² to about 0.470 oz-in². In yet another embodiment, the golf ball has a moment of inertia of from about 0.450 oz-in² to about 0.460 oz-in².

The following results reported in TABLE I demonstrate the superior and unexpected qualities achieved by a golf ball of the invention incorporating a coating system having at least three layers wherein each coating layer is different:

TABLE I Coating Example Golf Ball Coating Construction Durability* Adhesion Number IC ** INC *** OC**** Rating Rating Ex. 1 White¹ Translucent Clear³ 1 Excellent, Pearlescent² all layers Comp. Ex. 1 White¹ White¹ Pearl 4 Poor, Top Clear⁴ Coat to Mid coat *In TABLE I, golf balls are assigned a durability rating as defined in TABLE II based on the average of a 12 ball sample, wherein each golf ball is subjected to 200 hit pendulum testing. ** Herein, “IC” denotes “innermost coating”, the coating layer adjacent golf ball cover or outermost golf ball surface being coated. *** Herein, “INC” denotes “intermediate coating”, the coating layer surrounding the IC. ****Herein, “OC” denotes “outer coating”, the outermost coating layer. ¹A white coating layer @ 48% mixed solids and having a mixed viscosity of 20-25 seconds in a #2 Zahn Cup @ 77° F. The viscosity was measured using a Zahn Cup, which comes in 5 sizes, 1-5. Lower numbered cups are used to measure lower viscosity liquids. A Zahn Cup is a stainless steel cup bored with a very small hole in the bottom of the cup. The cup was completely filled with the coating material and the viscosity measured as the time it takes for the coating material, streaming through the hole, to break up, called the “efflux time”. See, e.g., http://www.guardco.com/pages/viscosity/vi/ez.cfm. ²A translucent pearlescent coating layer @ 50% mixed solids and having a mixed viscosity of 19-24 seconds in a #2 Zahn Cup @ 77° F. ³A clear coating layer @ 48% mixed solids and having mixed viscosity of 19-24 seconds in a #2 Zahn Cup @ 77° F. ⁴A pearl clear coating layer @ 48% mixed solids and having a mixed viscosity of 19-24 seconds in a #2 Zahn Cup @ 77° F.

Golf ball durability and coating adhesiveness were both evaluated for golf ball groups “Ex. 1” (inventive golf balls) and “Comp. Ex. 1” (comparative), each group consisting of 12 test golf balls. Across both groups, the substrates are identical, each comprising a solid core and a urethane cover. However, the coating systems in group Ex. 1 and group Comp. Ex. 1 are different. Specifically, the coating system in Ex. 1 comprises a white innermost coating¹ (IC), surrounded by an intermediate coating layer (INC) comprising a translucent pearlescent pigment², surrounded by a third and outermost coating layer (OC) comprising a transparent clear coating³. Meanwhile, the coating system in Comp. Ex. 1 comprises a white IC (identical to IC of Ex. 1), surrounded by a second white INC coating layer (identical to IC of Comp. Ex. 1, which is surrounded by an OC comprising a pearl clear (transparent) pigment⁴.

The durability of each golf ball was assessed by subjecting each golf ball to 200 hit pendulum testing and then visually inspecting and rating it according to the parameters detailed in TABLE II:

TABLE II Rating Paint 1 = Excellent No Coating loss 2 = Good Slight wear on dimple edges only 1-3 balls 3 = Fair Slight wear on dimple edges more than 3 balls 4 = Poor Loss of Coating between and on dimple edges 5 = Severe Any loss of coating within dimples

The results of these durability tests are recorded and appear in Table I under the heading “Durability Rating” and comprise an average of the durability ratings for the 12 golf balls in a particular group. As Table I reveals, a golf ball of the invention in Ex. 1 has an average durability rating of 1, significantly better than the average durability rating of 4 for comparable golf ball Comp. Ex. 1. Accordingly this data demonstrates that a golf ball of the invention incorporating a three layer coating system wherein each coating layer is different possesses significantly better durability than prior golf balls incorporating a three layer coating system wherein two of the three coating layers are identical.

Quality of adhesion between each coating layer was also assessed for groups Ex. 1 and Comp. Ex. 1 by inspecting the golf balls in both visible light and when exposed to ultra violet light. The clear topcoat contained a low level of florescent optical brightener which is visible only when exposed UV light. The inspection in visible light revealed loss of adhesion between the entire coating system and the substrate in the comparative golf balls. The inspection under UV light revealed loss of adhesion between the clear topcoat and underlying coating layers in the comparative golf balls. As recorded in TABLE I, adhesion between each coating layer on each golf ball in inventive golf balls group Ex. 1 is excellent as between each and every coating layer, whereas in comparative golf balls Comp. Ex. 1, adhesion was poor as between the OC clear coating layer and the INC white coating layer. Accordingly, this data demonstrates that a golf ball of the invention incorporating a three layer coating system wherein each coating layer is different possesses significantly better and consistent adhesion between coating layers than prior golf balls incorporating a three layer coating system wherein two of the three coating layers are identical.

The following non-limiting prophetic additional examples set forth in in TABLE III further illustrate the superior durability and adhesion achieved in a golf ball of the invention:

TABLE III Durability Rating Coating Example Golf Ball Coating Visual (Scale Adhesion No. Arrangement Appearance of 1-5) Rating 1 **IC: opaque White Golf 1 Similar white pigment Ball with Gold to Ex. 1 paint Pearl Luster ***INC: translucent gold pearl pearlescent paint ****OC: clear colorless paint 2 IC: opaque white Pale Yellow 1 Similar pigment paint Golf Ball with to Ex. 1 INC: translucent Gold Pearl gold pearl Luster pearlescent paint OC: clear coating yellow tinted 3 IC: opaque yellow Strong Yellow 1 Similar pigment paint Golf Ball with to Ex. 1 INC: translucent gold Pearl gold pearl Luster pearlescent paint OC: clear colorless coating 4 IC: opaque Vibrant yellow 1 Similar fluorescent golf ball with to Ex. 1 yellow/green gold pearl pigment paint luster INC: translucent gold pearl pearlescent paint OC: clear coating yellow tinted 5 IC: opaque white White Golf 1 Similar pigment paint Ball with Two to Ex. 1 INC: translucent Tone Luster gold pearl pearlescent paint OC: translucent green pearl pearlescent pigment 6 IC: opaque yellow Yellow Golf 1 Similar pigment paint ball with Two to Ex. 1 INC: translucent Tone Luster gold pearl pearlescent paint OC: translucent green pearl pearlescent pigment 7 IC: translucent Two Tone 1 Similar gold pearl yellow/green to Ex. 1 pearlescent paint Golf Ball with INC: translucent Two Tone green pearl Luster pearlescent pigment OC: clear colorless topcoat 8 IC: translucent Dominantly 1 Similar gold pearl Yellow Golf to Ex. 1 pearlescent paint Ball with Two INC: translucent Tone Luster green pearl pearlescent pigment OC: clear yellow tinted topcoat 10 IC: opaque white Orange Golf 1 Similar pigment paint Ball with Two to Ex. 1 INC₁: translucent Tone gold pearl Yellow/Red pearlescent paint Luster INC₂: translucent red pearl pearlescent paint⁹ OC: Clear colorless 11 IC: opaque white Predominantly 1 Similar pigment paint Strong Orange to Ex. 1 INC₁: translucent Golf Ball with gold pearl Two Tone pearlescent paint Yellow/Red INC₂: translucent Luster red pearl pearlescent paint₉ OC: Clear orange tinted topcoat 1C IC: opaque white White Golf 4 Similar paint Ball with to Comp. OC: clear paint Clear Pearl Ex. 1 with pigment Luster providing optical interference 2C IC: clear paint Dull White 4 Similar OC: clear paint Golf Ball with to Comp. with pigment Clear Pearl Ex. 1 providing optical Luster interference 3C IC: opaque white Dull White 4 Similar paint Golf Ball with to Comp. OC: translucent Clear Pearl Ex. 1 colorless paint Luster with pigment providing optical interference 4C IC: opaque red Red Golf Ball 4 Similar paint with to Comp. OC: clear paint interference Ex. 1 with pigment effects providing optical interference 5C IC: opaque yellow Pale yellow 4 Similar paint Golf Ball with to Comp. OC: translucent interference Ex. 1 paint with pigment effects providing optical interference 6C IC: opaque white White Golf 4 Similar paint Ball to Comp. INC: opaque white Ex. 1 paint OC: clear coating 7C IC: white paint Dull White 4 Similar INC: clear coating Golf Ball to Comp. OC: clear coating Ex. 1 *In TABLE III, the durability is measured and defined using the same methodology set forth in TABLE II.

One benefit of an embodiment of the golf ball of the invention such as Ex. 1 of TABLE I is that any flakes or other particles contained in the pearlescent coating are sealed within the intermediate (INC) coating by the outermost (OC) coating, thereby reducing vulnerability made possible by flakes, etc. in the outer surface.

Any of the embodiments herein may have any known dimple number, pattern, width, depth, and/or edge angle and pattern. The parting line configuration of said pattern may be either a straight line or a staggered wave parting line (SWPL).

Unless otherwise expressly specified, all of the numerical ranges, amounts, values and percentages such as those for amounts of materials, and others in the specification may be read as if prefaced by the word “about” even though the term “about” may not expressly appear with the value, amount or range. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Furthermore, when numerical ranges of varying scope are set forth herein, it is contemplated that any combination of these values inclusive of the recited values may be used.

While it is apparent that the illustrative embodiments of the invention disclosed herein fulfill the preferred embodiments of the present invention, it is appreciated that numerous modifications and other embodiments may be devised by those skilled in the art. Examples of such modifications include reasonable variations of the numerical values and/or materials and/or components discussed above. Hence, the numerical values stated above and claimed below specifically include those values and the values that are approximate to those stated and claimed values. Therefore, it will be understood that the appended claims are intended to cover all such modifications and embodiments, which would come within the spirit and scope of the present invention.

The invention described and claimed herein is not to be limited in scope by the specific embodiments herein disclosed, since these embodiments are intended as illustrations of several aspects of the invention. Any equivalent embodiments are intended to be within the scope of this invention. Indeed, various modifications of the invention in addition to those shown and described herein will become apparent to those skilled in the art from the foregoing description. 

What is claimed is:
 1. A golf ball comprising: a core and a cover disposed about the core; an innermost coating layer C₁ surrounding the cover; an intermediate coating layer C₂ surrounding C₁; and an outermost coating layer C₃ surrounding C₂; wherein C₁ has a first color appearance A₁, C₂ has a second color appearance A₂, and C₃ has a third color appearance A₃ such that A₁≠A₂≠A₃ and wherein A₁, A₂, and A₃ each contribute to an overall golf ball color appearance.
 2. The golf ball of claim 1, wherein the cover comprises at least one of a urethane and a balata composition.
 3. The golf ball of claim 1, wherein the cover comprises an ionomeric resin.
 4. The golf ball of claim 1, wherein C₁ is opaque and comprises a white pigment, C₂ is translucent and comprises a pearlescent pigment, and C₃ is transparent.
 5. The golf ball of claim 4, wherein C₃ is colorless.
 6. The golf ball of claim 4, wherein C₃ is transparent colored.
 7. The golf ball of claim 4, wherein the pearlescent pigment is a gold pearlescent pigment.
 8. The golf ball of claim 1, wherein C₁ is opaque and comprises a white pigment, C₂ is translucent and comprises an interference effect pigment, and C₃ is transparent.
 9. The golf ball of claim 1, wherein C₁ is opaque and comprises a pigment other than white, C₂ is translucent and comprises a pearlescent pigment, and C₃ is transparent.
 10. The golf ball of claim 9, wherein C₃ is colorless.
 11. The golf ball of claim 9, wherein C₃ is transparent colored.
 12. The golf ball of claim 1, wherein C₁ is opaque and comprises a pigment other than white, C₂ is translucent and comprises an interference effect pigment, and C₃ is transparent.
 13. The golf ball of claim 1, wherein C₁ is translucent and comprises a pearlescent pigment P₁, C₂ is translucent and comprises a pearlescent pigment P₂ wherein P₁ is different than P₂, and C₃ is transparent.
 14. The golf ball of claim 13, wherein C₃ is colorless.
 15. The golf ball of claim 13, wherein C₃ is transparent colored.
 16. The golf ball of claim 1, wherein C₁ has a transmittance T₁, C₂ has a transmittance T₂ and C₃ has a transmittance T₃ such that T₁≠T₂≠T₃.
 17. The golf ball of claim 1, wherein C₁ has a reflectance R₁, C₂ has a reflectance R₂, and C₃ has a reflectance R₃ such that R₁≠R₂≠R₃.
 18. A golf ball comprising: a core and a cover disposed about the core; a three layer coating disposed about the cover comprising a innermost coating layer adjacent the cover, an intermediate coating layer surrounding the innermost coating layer, and an outermost coating layer surrounding the intermediate coating layer; wherein each coating layer has a different color appearance that contributes to an overall golf ball color appearance producing a color traveling effect.
 19. A golf ball comprising a core, a cover disposed about the core, and C_(n) coating layers formed about the cover wherein n≧3, and wherein at least three of C_(n) coating layers has a different color appearance that contributes to an overall color appearance.
 20. The golf ball of claim 19, wherein n=4 such that: C₁ and C₂ are both opaque and comprise a white pigment; C₃ is translucent and comprises an interference effects pigment; and C₄ is transparent.
 21. The golf ball of claim 20, wherein C₄ is colorless.
 22. The golf ball of claim 20, wherein C₁, C₂, C₃, and C₄ have corresponding transmittances C_(1T), C_(2T), C_(3T), and C_(4T) such that C_(1T) is substantially similar to C_(2T) and C_(2T)≠C_(3T)≠C_(4T).
 23. The golf ball of claim 20, wherein C₁, C₂, C₃, and C₄ have corresponding reflectances C_(1R), C_(2R), C_(3R), and C_(4R) such that C_(1R) is substantially similar to C_(2R) and C_(2R)≠C_(3R)≠_(4R).
 24. A golf ball comprising: a core and a cover disposed about the core; and three coating layers formed about the cover comprising an innermost coating layer adjacent the cover, an intermediate coating layer surrounding the innermost coating layer, and an outermost coating layer surrounding the intermediate coating layer; wherein each of the three coating layers has a spectral reflectance and a spectral transmittance such that at least one of the spectral reflectance and the spectral transmittance of each of the three coating layers is different.
 25. The golf ball of claim 24, wherein the reflectance of at least one coating layer is specular and the reflectance of at least one coating layer is diffuse.
 26. The golf ball of claim 24, wherein the transmittance of at least one coating layer is diffuse and the transmittance of at least one coating layer is regular. 